Sponge
Give the ionic compound for the following:
1.
K+ + O22.
Sr2+ + Cl3.
Na+ + F4.
Fe3+ + Cl-
IONIC BONDING PART 2
Chemistry
Unit 3, Day 2
Properties of Ionic Compounds
• Crystal Lattice Structure
• Each positive ion is
surrounded by negatives
• Each negative ion is
surrounded by positives
• Strong Bonds
• Require large amounts of
energy to break apart
• High melting points
• High boiling points
• Hard, Rigid, Brittle solids
Strength of the Bond
• Energy required to
separate one mole of
the ions of an ionic
compound is referred
to as Lattice Energy
• The more negative the
energy, the stronger
the force of attraction,
the harder to separate
ions
Compound Lattice
Energy
(kJ/mol)
KBr
-671
NaBr
-732
AgCl
-910
SrCl2
-2142
RECALL: Writing Formula Units
• The formula unit (product)
• Li+ and O2-
must be neutral (zero
charge)
• Add the ions involved
• The cation is written first,
then the anion
+1
-2
= -1 charge, need +
• Li+ + O2- + Li+
+1
-2
+1
= 0 charge, check!
• Li2O
Oxidation Numbers
• The charge on the ion is called its oxidation
number or oxidation state
• Atoms can have more than one oxidation number
Naming Monatomic Ionic Compounds
• Monatomic- an ion made up of one type of atom (Li+, Na+,
O2-, etc.)
• The cation is given its full name
• The anion uses the suffix –ide
• For example, Li+ and O2• Lithium Oxide
• For example, Na+ and Cl• Sodium Chloride
Think-Pair-Share: complete the chart by creating the
formula unit. Leave room to also include the name of the compound.
Na+
F-
O2-
N3-
S2-
1 NaF
2 Na2O
3 Na N
3
4 Na2S
Sodium
Fluoride
Li+
Mg2+
Be2+
5 LiF
Lithium
Fluoride
9 MgF2
Magnesium
Fluoride
13 BeF2
Beryllium
Fluoride
Sodium Oxide
6 Li2O
Lithium Oxide
10 MgO
Magnesium
Oxide
14 BeO
Beryllium
Oxide
Sodium
Sulfide
Sodium Nitride
7 Li3N
Lithium Nitride
11 Mg3N2
Magnesium
Nitride
15 Be3N2
Beryllium
Nitride
8
Li2S
Lithium Sulfide
12 MgS
Magnesium
Sulfide
16 BeS
Beryllium
Sulfide
Guided Practice – reading charts
Compound
KI
Lattice Energy
(kJ/mol)
-632
Melting Point
(˚C)
681
KF
-808
858
• Which is a stronger bond? Why?
• KF, more negative energy
• Which has a higher melting point?
• KF
• What is the relationship between ionic bond strength and melting
point?
• The stronger the bond, the higher the melting point!